Dynamic Compressive Loading Research Articles

Mechanical response to dynamic compressive load applied to shale after thermal treatment

In deep shale gas extraction, high temperature environment and dynamic loads are two important factors in affecting reservoir reconstruction and shale breaking. By employing the test techniques of Split Hopkinson pressure bar, dynamic compressive mechanical response of shale specimens with five different bedding dips after thermal treatment of 25–200 °C was investigated under the same impact energy. Results reveal that the increasing thermal treatment temperature weakens the post-peak behavior in stress-strain curves of specimens with bedding dips of 0°, 30° and 90°, and strengthens that of specimens with bedding dips of 45° and 60°. The dynamic compression strength variation of specimens versus increasing thermal treatment temperature shows two opposite trends bounded by the bedding dip of 30°. With increasing thermal treatment temperature, failure mode of specimens with bedding dips of 45° and 60° is affected evidently, but that of specimens with bedding dips of 0°, 30° and 90° has no fundamental change. The increasing thermal treatment temperature impacts the amount of absorbed energy in one of two ways depending on the bedding dip, and increases the dynamic fragmentation degree of all specimens, but that of specimens with bedding dips of 45° and 60° is much larger. Furthermore, the dynamic anisotropy of specimens after thermal treatment and its possible application in deep shale gas extraction are discussed. Results can be beneficial to the perforation design in hydraulic fracturing and the dynamic fracturing technology development in deep shale reservoirs.

A porosity-based model of dynamic compaction in under-dense materials

Under-dense metals including micro-architectured structures and stochastic foams provide a combination of low weight, high strength-to-weight ratio, high permeability, and low stiffness, which make them desirable materials for a variety of applications. Specifically, their energy absorption capabilities under dynamic compressive loads are desirable. However, under high loading rates there are several challenges in performing accurate simulations of under-dense materials—primarily, the responses of materials with high, low, and zero porosity are difficult to accurately predict with a single model. A general model that tracks porosity and pore geometry and is flexible for a variety of matrix material constitutive responses has yet to be produced. This work outlines such a model and applies it to high loading rate simulations that demonstrate the model’s ability to address a variety of stress states. The approach is to extend a porosity model meant for isolated porosity of low-to-modest volume fraction to the application space of under-dense materials. Calibration parameters are used to account for complex mechanisms as well as the effects of the geometries of various under-dense materials. This results in a general, versatile, and flexible model. A study of the model’s sensitivity to calibration parameters is shown along with qualitative and quantitative comparisons to direct numerical simulations (DNS) and predictions resulting from impact velocities and flyer structures for which the model is not calibrated. This model can simulate a range of compaction conditions and is less computationally intense than direct numerical simulations which gives it utility in the design of micro-architected materials for impact mitigation, energy absorption, and other applications.

Experiment and mesoscopic modelling on the dynamic compressive behaviors of a new carbon fiber-reinforced cement-based composite

This paper presents an experimental and numerical study on the compressive behaviors of a new carbon fiber-reinforced cement-based composite (CFRCC) that is composed of magnesium oxysulfate cement, carbon fiber and some chemical admixtures. Parametric studies on the effects of carbon fiber content and strain rate on the compressive behaviors of CFRCC, are conducted using a series of quasi-static and dynamic compressive tests. The research item includes the failure morphology, stress-strain curve, dynamic increase factor (DIF), etc. Besides, a three-dimensional (3D) mesoscale modelling approach is proposed to simulate and analyze the mechanical responses and the failure mechanisms of CFRCC subjected to dynamic compressive loading, where the random dispersion of chopped fibers are realistically considered. The results indicate that the cracking and failure modes of CFRCC are significantly affected by the bridging effect of carbon fibers randomly dispersed in cement matrix. With the increase of fiber content, the dynamic peak stress and peak strain of CFRCC at similar strain rates show an increasing and decreasing trend, respectively. An evident strain-rate hardening effect could be found on the initial elastic modulus and the peak stress of CFRCC as well. While the relationship between the DIF of CFRCC and the logarithm of strain rate could be described using a quadratic function. Moreover, the mesoscale modelling approach has been validated by a good agreement between the numerical and tested results, demonstrating the feasibility of the developed mesoscale model in simulating and investigating the dynamic behaviors of CFRCC. All in all, the CFRCC has proven to be of great significance in resisting to impact loads, and more insights should be provided into its dynamic properties.

Experimental investigation of 3D-printed auxetic core sandwich structures under quasi-static and dynamic compression and bending loads

Auxiliary metamaterials designed according to the Negative Poisson’s Ratio (NPR) property are exciting structures due to their high impact strength, impact energy absorption abilities, and different damage mechanisms. These good mechanical features are suitable for aviation, automotive, and protective construction applications. These structures, whose most significant disadvantages are production difficulties, have become easier to produce with the development of 3D production technology and have been the subject of many studies in recent years. In this presented study, two conventional core geometries and three different auxetic geometries, commonly used in sandwich structures, were designed and produced with 3D printer technology. The strength and energy absorption capabilities of prototype sandwich structures investigated experimentally under bending loads with static and dynamic compression. Except for the re-entrant (RE) type core, the auxetic core foam sandwich structures demonstrate higher rigidity and load-carrying capacity than classical sinusoidal corrugated (SC) core and honeycomb (HC) core sandwich structures under both quasi-static and impact-loaded compression and three-point bending experiments. Double arrowhead (DAH) and tetrachiral (TC) auxetic cores outperformed honeycomb core in terms of specific quasi-static and impact load-bearing performance under compression by 1.5 ± 0.25 times. In three-point bending experiments under both quasi-static and impact loading conditions, the load-carrying capacity of the double arrowhead and tetrachiral auxetic cores was found to be more than 1,86 ± 0.38 times that of the honeycomb core sandwich panels.

Failure tolerance of the human lumbar spine in dynamic combined compression and flexion loading

Vehicle safety systems have substantially decreased motor vehicle crash-related injuries and fatalities, but injuries to the lumbar spine still have been reported. Experimental and computational analyses of upright and, particularly, reclined occupants in frontal crashes have shown that the lumbar spine can be subjected to simultaneous and out-of-phase combined axial compression and flexion loading. Lumbar spine failure tolerance in combined compression-flexion has not been widely explored in the literature. Therefore, the goal of this study was to measure the failure tolerance of the lumbar spine in combined compression and flexion. Forty lumbar spine segments with three vertebrae (one unconstrained) and two intervertebral discs (both unconstrained) were pre-loaded with axial compression (2200N, 3300N, or 4500N) and then subjected to rotation-controlled dynamic flexion bending until failure. Clinically relevant middle vertebra fractures were observed in twenty-one of the specimens, including compression and burst fractures. The remaining nineteen specimens experienced failure at the potting-grip interface. Failure tolerance varied within the sample and were categorized by the appropriate data censoring, with clinically relevant middle vertebrae fractures characterized as uncensored or left-censored and potting-grip fractures characterized as right-censored. Average failure force and moment were 3290N (range: 1580N to 5042N) and 51Nm (range: 0Nm to 156 Nm) for uncensored data, 3686N (range: 3145N to 4112N) and 0Nm for left-censored data, and 3470N (range: 2138N to 5062N) and 101Nm (range: 27Nm to 182Nm) for right-censored data. These data can be used to develop and improve injury prediction tools for lumbar spine fractures and further research in future safety systems.

Mechanical behavior and damage kinetics of a unidirectional carbon/epoxy laminated composite under dynamic compressive loading

AbstractIn this work, mechanical behavior and damage kinetics of a unidirectional carbon/epoxy laminated composite (CFRP) under dynamic compressive loading were investigated. An Instron testing machine and a pulse‐shaped split Hopkinson pressure bar (SHPB) apparatus were employed to test the quasi‐static and dynamic mechanical properties of the material, respectively. Digital image correlation (DIC) combined with ultra high‐speed photography was used to study the deformation and failure process of the specimen under dynamic loading. The results show that the failure modes of the material along the main direction were strain‐rate sensitive. The failure mode along the fiber direction was observed to change from crushing followed by fiber kink banding to predominantly interlaminar delamination, longitudinal cracking and fiber buckling delamination as the strain rate increases from quasi‐static to high strain rates. Furthermore, an empirical formula for dynamic compression strength was established based on the test data. Model predictions and experimental data are in very good agreement. Finally, a simplified Zhu‐Wang‐Tang (ZWT) nonlinear visco‐hyperelastic constitutive model ZWT nonlinear viscoelastic model was developed to predict the mechanical behaviors of CFRP under dynamic impact loading. The predicted values are observed to essentially match the trends of the experimental results. This research will further improve the design of CFRP composites subjected to high‐speed impact loads during service.

Effect of temperature and strain rate on the formation of shear bands in polymers under quasi-static and dynamic compressive loadings: Proposed constitutive model and numerical validation

The mechanical behaviour of polymers is strongly influenced by temperature and strain rate conditions. Their effects are clearly observed in the Young modulus and Yield strength assessment. In some cases, a change in material failure mode can be noted, which can be both ductile and brittle. For polymers exhibiting shear bands during compression loading, test conditions may enhance or diminish this effect. In this study, isotactic Polypropylene has been considered due to its strong sensitivity to test conditions; with some combinations of strain rate and temperature, the material is able to undergo large compression with nearly uniform strain distribution, whereas significant shear bands can be observed with other strain rate and temperature combinations. This paper proposes a constitutive law for the mechanical characterization of polymers that show shear banding in compression loading. The proposed law extends a visco-plastic model present in literature, allowing to predict the onset or not of micro-shear banding compression instability. The dependence of constitutive parameters with test conditions is determined by applying the Ree-Eyring equation. The model parameters have been calibrated analytically according to experimental data obtained from compression tests performed in a wide range of strain rates (10−3 to 103 1/s) and temperatures (253–313 K). In addition, the constitutive model has been implemented in a commercial FEM code by means of a user-defined subroutine. Results show a good correspondence between experimental observations and numerical calculations, regarding both stress-strain relationship and shear band formation.

Experimental Study on Static and Dynamic Response of Aluminum Honeycomb Sandwich Structures.

Honeycomb aluminum structures are used in energy-absorbing constructions in military, automotive, aerospace and space industries. Especially, the protection against explosives in military vehicles is very important. The paper deals with the study of selected aluminum honeycomb sandwich materials subjected to static and dynamic compressive loading. The used equipment includes: static strength machine, drop hammer and Split Hopkinson Pressure Bar (SHPB). The results show the influence of applied strain rate on the strength properties, especially Plateau stress, of the tested material. In each of the discussed cases, an increase in the value of plateau stresses in the entire strain range was noted with an increase in the strain rate, with an average of 10 to 19%. This increase is mostly visible in the final phase of structure destruction, and considering the geometrical parameters of the samples, the plateau stress increase was about 0.3 MPa between samples with the smallest and largest cell size for the SHPB test and about 0.15 MPa for the drop hammer test.

Dynamic strain field for granite specimen under SHPB impact tests based on stress wave propagation

The full-field strain of rock material under dynamic compression load was studied using the high-speed three dimensional digital image correlation (3D-DIC) method. The dynamic test was conducted on Laizhou granite using a split Hopkinson pressure bar (SHPB) method. Wave propagation, dispersion and radial inertial effect on the specimen were found by DIC results. A recovery of strain in the post-peak stage was detected on the specimen by DIC, which was unrevealed in the traditional one-dimensional theory method. It can be found that the strain measured by strain gauge was a calculated average one, whereas the strain measured by 3D-DIC could reflect more variation details. Specifically, the testing principle with impact loads and rock dynamic behavior was re-examined using stress wave propagation theory. The theoretical results showed that the specimen reached equilibrium after a series of wave reflections and transmissions and its stress was infinitely close to the initial value of 109.2 MPa. Moreover, the specimen had the calculated maximum strain of 0.52% and strain rate of 15.11 s−1, improving the reasonable agreement with the experimental results and requirements of rock mechanical properties measured by SHPB technology.

Reaction Forces and Flexion-Extension Moments Imposed on Functional Spinal Units With Constrained and Unconstrained In Vitro Testing Systems.

A mechanical goal of in vitro testing systems is to minimize differences between applied and actual forces and moments experienced by spinal units. This study quantified the joint reaction forces and reaction flexion-extension moments during dynamic compression loading imposed throughout the physiological flexion-extension range of motion. Constrained (fixed base) and unconstrained (floating base) testing systems were compared. Sixteen porcine spinal units were assigned to both testing groups. Following conditioning tests, specimens were dynamically loaded for 1 cycle with a 1 Hz compression waveform to a peak load of 1 kN and 2 kN while positioned in five different postures (neutral, 100% and 300% of the flexion and extension neutral zone), totaling ten trials per functional spinal unit (FSU). A six degree-of-freedom force and torque sensor was used to measure peak reaction forces and moments for each trial. Shear reaction forces were significantly greater (25.5 N-85.7 N) when the testing system was constrained compared to unconstrained (p < 0.029). The reaction moment was influenced by posture (p = 0.037), particularly in C5C6 spinal units. In 300% extension (C5C6), the reaction moment was, on average, 9.9 N·m greater than the applied moment in both testing systems and differed from all other postures (p < 0.001). The reaction moment error was, on average, 0.45 N·m at all other postures. In conclusion, these findings demonstrate that comparable reaction moments can be achieved with unconstrained systems, but without inducing appreciable shear reaction forces.

Effect of Strain Rate Sensitivity on Fracture of Laminated Rings under Dynamic Compressive Loading

The effects of cladding layers of rate-sensitive materials on the ductility and fracture strain of compressed rings are numerically investigated by using the finite element method (FEM) and employing the Johnson–Cook (J–C) model. The results show that ductility is governed by the behavior of the material that is located at the ring outer wall regardless of the volume fraction of the core and clad materials. However, as the number of layers increases, this influence becomes less noticeable. Moreover, as barreling increases at the outer wall and decreases at the inner wall, fracture strain increases. Furthermore, the effects of ring shape factor and bonding type of clad and core materials are numerically evaluated. The numerical results show that less force per unit volume is required to fracture narrower rings and that using a noise diffusion pattern at the interface of the materials is more suitable to simulate crack propagation in the compressed rings and functionally graded materials (FGMs). Additionally, delamination has a direct relation to layer thickness and can occur even in the presence of perfect bonding conditions owing to differences among the material and fracture parameters of laminated layers.

Microstructure and mechanical properties of extrusion ZC61 alloys under different dynamic compression loading directions

The dynamic mechanical properties and microstructure of Mg-5.9Zn-0.9Cu-0.4Zr (ZC61) alloy are systematically investigated at strain rate of 1100–2200 s−1, which is manufactured by severe plastic deformation (SPD) processes, i.e. combines traditional hot extrusion with equal channel angular pressing. The microstructural observation reveals that fine equiaxed grains are formed after the hot extrusion-shear process, and the average size of extrusion direction (ED) and extrusion radial direction (ERD) is found to be 41 µm and 32 µm, respectively. The dynamic compression curves exhibit that the peak flow stress improves with increasing strain rate, which shows a positive strain rate enhancement effects. At 2200 s−1 strain rate, the ultimate compression strength of alloy along ED and ERD is found to be 581 MPa and 530 MPa, respectively. During dynamic compression, for ED sample, the {101̅2} extension twinning is observed to be the major plastic deformation mechanism, and the fracture surface exhibits brittle rupture and local melting. Whereas, for ERD sample, the {101̅2} extension twinning and {101̅1}-{101̅2} secondary twinning (37.5° < 112̅0 >) are found to be dominant deformation mechanisms, and the fracture mode is mainly brittle rupture.

Nonlinear Young\u2019s Modulus of New Red Sandstone: Experimental Studies

Young’s modulus of New Red Sandstone was investigated experimentally to gain insight into its nonlinear nature. A large experimental programme was carried out by applying a controllable quasi-static and dynamic uniaxial loading to 286 dry sandstone samples of four different sizes. The static and dynamic tests, similar to those aiming at determining the uniaxial compressive strength, were conducted using the state-of-the-art experimental facilities at the University of Aberdeen including a custom-built small experimental rig for inducing a dynamic uniaxial compressive load via a piezoelectric transducer. The obtained results have confirmed a complex nature of Young’s modulus of sandstone. Specifically, under a harmonic dynamic loading, it shows strongly nonlinear behaviour, which is hardening and softening with respect to frequency and amplitude of the dynamic loading, respectively.

Experimental Investigation on Multiscale Fracturing in Thermally Treated Sandstone under SHPB Impact Loading

To study the effect of temperature on the dynamic mechanical behaviors and fracture characteristics of thermally treated sandstone, compressive dynamic loading experiments were performed on a series of samples using a split Hopkinson pressure bar (SHPB). In the tests, the dynamic uniaxial compressive strength of the thermally treated sandstone was inversely proportional to the temperature treatment in the range of 200°C–1000°C, while the dynamic elastic modulus first increased and then gradually decreased after different temperature treatments. The results show that two classical mechanical types (i.e., Class I and Class II) are observed from the dynamic stress-strain responses of SHPB tests for thermally treated sandstone. By means of scanning electron microscopy (SEM), the microdifference of postloading microfracture characteristics in Class I and Class II behavior was identified. In Class I behavior, intercrystalline cracks (IE) are the chief form of cracks on the fracture surface of a specimen fractured by SHPB loading even though there some intracrystalline cracks may also be present. In contrast, Class II behavior results from the chief cracking type being intracrystalline cracks.

Dynamic Compressive Strength of Recycled Aggregate Concrete

Over the years the construction waste has enormously increased, this may be attributed to different factors such as (i) demolition (ii) accidents (iii) impact loads (iv) earthquakes. These activities have caused an increasing burden on already exhausted waste management system globally. As a result, the concrete waste produced in a large quantity has become a major issue to manage due to limited landfill sites. Therefore, the recycling of waste concrete can prove to be beneficial and necessary for the environmental preservation and effective utilization of natural resources. Number of studies have been conducted to study the static mechanical properties of recycled aggregate concrete; however, limited test data has been published which focused on the dynamic properties of the concrete prepared with recycled coarse aggregates. Therefore, in this investigation aim was to study the behavior of recycled aggregates concrete under increasing dynamic compressive loading. For this purpose, cylindrical specimens having a diameter of 100 mm and height of 200 mm were used. These specimens have been prepared with constant concrete mix ratio, having varying percentages of RA such as 0%, 30%, and 50% 70 % and 100%. The dynamic compressive behaviour was studied by using drop hammer system. The height drop hammer system consist of a frame having a maximum height of 15ft. Firstly, three samples (1, 1R, 2R) from each percentage replacement (0%, 30%, 50%, 70% and 100%) were tested on six different velocities of 2.44m/s, 3.45m/s, 4.23m/s, 4.89m/s, 5.46m/s and 7.45m/s with varying strain rates of 12.04/s, 17.00/s, 20.83/s, 24.08/s, 26.89/s and 36.73/s respectively. Weight of the drop hammer was 10 kg. Based on the detailed experimental investigation, it was found that the behaviour of the recycled aggregate concrete under dynamic loading differ significantly from the static loading.

Nanomodified Cementitious Composites Incorporating Basalt Fiber Pellets under Tensile and Impact Loads

This study investigated the behavior of nanomodified cementitious composites reinforced with innovative basalt fiber pellets (BFP), with specially tailored surface texture under quasi-static (direct) tensile as well as static and dynamic compression (split Hopkinson pressure bar) loading schemes. The composites comprised two different binder formulations (50% fly ash or slag replacement) with/without nanosilica modification. Thermogravimetric and microscopy studies were conducted to evaluate the hydration development and microstructure of the binders. Moreover, the pellet/matrix interfacial bond properties were assessed using the single pellet pullout test. The results showed the efficacy of BFP in reinforcing the cementitious composites and highlighted the role of nanosilica at enhancing the postcracking performance of high-volume fly ash– and slag-based mixtures under all loading schemes. Furthermore, the increase of the pellets’ dosage improved the ductility of composites in terms of energy absorption capacity and strain at failure. The pellet/matrix interface, which is responsible for the main toughening mechanism of the composites by pullout, was sensitive to the type of binder and imposed displacement rate.

The Effect of mechanical loading cycles on different abutment types in implants with tapered internal connection

Aim The purpose of this in vitro study was to evaluate the influence of the application of cyclic mechanical load on torque loss and on the seating installation of internal tapered abutments. Materials and methods Forty tapered implants and 40 abutments were used and divided into four groups (n=10): Group 1 (Titamax CM) and Group 2 (Strong SW Morse) received one-piece abutments; Group 3 (Titamax CM) and Group 4 (Strong SW Morse) received two-piece abutments. Tightening torque and reverse torque were applied, after 5 minutes, on all abutments. After that, tightening torque was applied to all the abutments, and were mechanically loaded and uninstalled. The two-piece abutments of Group 3 and Group 4 were divided in two subgroups (Subgroup 3a and Subgroup 4a: traction test required to remove the implant - pull out). The specimens were submitted to fatigue tests consisting of 1.200.000 cycles at a frequency of 2 Hz, dynamic compressive load of 50 N, and an angle of 30°. Data were analyzed through the normal distribution (Shapiro-Wilk, p> 0.05), followed by parametric statistical tests. Results After mechanical loading torque loss was higher in Group 4 (over 70% loss), followed by Group 1, Group 2 and Group 3 (over 50% loss). Group 1 and Group 2 presented no statistical difference. Subgroup 3a presented higher traction strength seating in post removal after mechanical loading (67.91 N), while Subgroup 4a presented only 1.92 N, it may present greater loosening of abutments. Conclusions The mechanical load significantly reduced the removal torque of the four groups of abutments tested, in addition to increasing frictional lock installation to the abutments of Subgroup 3a in the pull out test.

Compression properties and impact energy release characteristics of TiZrNbV high-entropy alloy

To explore the potential of high-entropy alloys (HEAs) as energetic structural materials (ESMs), the compression behaviors and impact energy release characteristics of TiZrNbV HEA were investigated. Mechanical experiments at strain rates from 1 × 10−3 s−1 to 1 × 104 s−1 showed that TiZrNbV HEA exhibits clear dynamic brittle fracture behavior under dynamic compression loading, which is diametrically opposite to its behavior under quasi-static compression loading. A Johnson–Cook constitutive model for TiZrNbV HEA was obtained by fitting the experimental data, which demonstrated an apparent strain rate effect. Numerical simulation and microstructure results revealed the role of an adiabatic shear band (ASB) in the brittle fracture. The crack profiles that evolved from the ASB exhibited the typical characteristic for high temperatures. The degree and rate of the chemical reaction and recycled products of direct ballistic tests indicated that severe oxidation reactions induced by the high-temperature profiles resulted in chemical energy release under impact loading. The relationship between the material microstructure and macromechanical behavior of TiZrNbV HEA, which is important in the use of HEAs as ESMs, was revealed in this study through mechanical and material methods and finite element numerical simulation.

Anti-inflammatory effects of tibial axial loading on knee articular cartilage post traumatic injury

Early therapeutic intervention to mitigate inflammatory responses following joint injury may offer a potential strategy to prevent post-traumatic osteoarthritis (PTOA). In-vitro studies have demonstrated uniaxial dynamic compression mitigates the catabolic and apoptotic responses of articular cartilage (AC) in response to mechanical injury. The objectives of this study were (1) to develop a custom device that can apply dynamic tibial axial loading (TAL) to knee AC by mimicking therapeutic, in-vitro loading conditions and (2) to investigate the potential of TAL to reduce the inflammatory response of AC post traumatic acute joint injury using an ex-vivo porcine model. A TAL device was fabricated to apply dynamic compressive loading to knee AC by combining tibial axial compressive loading with continuous passive motion. Computational analyses demonstrated that the loading condition applied to the knee by the TAL device closely simulate uniaxial dynamic compression reported in previous in-vitro studies. Following single impact injury, injured porcine knees were subjected to TAL with a magnitude of 1/4 body weight at a frequency of 1 Hz for 30 min. AC samples were harvested 8 h post injury for analysis of pro-inflammatory cytokine expression (IL-1β and TNF-α). Expression of both cytokines was upregulated following injury; however, the change was notably mitigated in the specimens subjected to TAL. Thus, TAL may be an effective and potentially, practical-to-administer early intervention strategy to mitigate rapidly occurring detrimental events following acute AC injury, potentially slowing down progression to PTOA.

Effect of water-based working fluid imbibition on static and dynamic compressive properties of anisotropic shale

In the shale gas extraction, drilling and hydrofracturing bring large amounts of water-based working fluid into shale reservoirs, which much affects the wellbore stability and gas production rate. To investigate the effect of water-based working fluid imbibition on static and dynamic compressive properties of anisotropic shale, the INSTRONG 1346 electro-hydraulic servo system and a modified Split Hopkinson pressure bar test system were used to perform the static and dynamic compressive tests on the dry and water-saturated shale specimens with bedding plane inclinations of 0°, 30°, 45°, 60° and 90°. Results reveal that the water imbibition process can be divided into three stages, and the chemical water-shale interaction may occur at the second stage. Under static and dynamic compressive loading, water imbibition can seriously weaken the strength and elastic modulus of specimens with the five different bedding plane inclinations, but increase the failure strain. Under the two loading forms, the relationship between compressive parameters of water-saturated specimens and the bedding plane inclination shows the same evolution trend as that of dry specimens, and the compressive parameters are affected the greatest by water imbibition when the bedding plane inclination is 45° or 60°. Furthermore, the mechanism of strength deterioration and the quantitative evaluation on anisotropy of dry and water-saturated specimens under the static and dynamic compressive tests are analyzed and discussed.